*2.1. Arc Deposition Methods*

CrAl-based and AlCr-based coatings are deposited by reactive direct vacuum arc using either elemental cathodes or composite cathodes. The first (CrAl)N and (AlCr)N coatings were deposited by the reactive co-evaporation of elemental chromium and aluminium cathodes available at that time [17–19].

The first composite cathodes suitable for arc evaporation manufactured by a powder metallurgical process were produced by Plansee AG, Austria, and were used successfully for tool coatings in 1995 [38]. Later, composite cathodes became the standard, especially in industrial applications [39,40]. A special pulsed process was developed for alpha (Al1−*x*Cr*x*)2O3 coatings, the P3e process [23]. The main goal of the pulsing is to overcome process difficulties generated by the oxide process (cathode, anode reactions).
